<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script>
    var o1 = { a: 1, b: 1, c: 1 };
    var o2 = { b: 2, c: 2 };
    var o3 = { c: 3 };

    var obj = Object.assign({}, o1, o2, o3);
    console.log(obj); // { a: 1, b: 2, c: 3 }
</script>
</html>